Enzymes: Roles and Regulations

Enzymes

Enzymes play a crucial role in clinical diagnosis and treatment. They are biological molecules that speed up chemical reactions without being consumed by them, enabling cellular processes such as digestion, absorption, respiration, exercise, and reproduction. Understanding enzymes is essential for understanding how cells function.

Inhibitors of Enzymatic Activity

Inhibitors can regulate enzymatic activity. These compounds bind to enzymes, reducing their ability to perform their functions. Inhibitors can be used therapeutically to reduce enzyme activity in certain conditions. For example, aspirin reduces platelet aggregation through its effect on cyclooxygenase, which ultimately helps prevent blood clots. Other inhibitors like statins block the HMG-CoA reductase enzyme, lowering cholesterol levels [1, 2].

Regulation of Enzymatic Activity

Enzyme activity can be regulated at multiple levels:

• Transcriptional regulation: Genetic factors control whether genes encoding specific enzymes are transcribed into mRNA. Some enzymes are made only when needed under specific conditions.

• Posttranslational modifications: Once synthesized, enzymes may undergo changes in structure that alter their activity. These modifications can be reversible, allowing the enzyme to change its behavior in response to different signals.

• Allosteric regulation: Some enzymes have multiple binding sites, allowing them to be influenced by other molecules. These interactions can either activate or inhibit the enzyme's activity.

Isozymes in Diagnosis of Pathologies

Isoenzymes are multiple forms of an individual enzyme that differ slightly but share a common function. They are produced from different genes within the same gene family and may vary depending on tissue type. For example, isoenzymes of lactate dehydrogenase (LDH) are important markers for diagnosing myocardial infarction: LDH-1 and LDH-2 levels in blood samples are higher after myocardial infarction than in healthy individuals.

Other common isozymes used in clinical diagnosis include:

• Creatine kinase (CK): Two main types of creatine kinase exist: CK-MB (muscle-brain) and CK-MM (muscle-muscle). Both forms can indicate muscle damage, but CK-MB specifically indicates myocardial infarction because it is predominantly found in heart tissue.

• Lipases: These enzymes play a role in digesting dietary lipids. In the context of diseases, lipase activity may increase due to pancreatitis or inflammation affecting fat metabolism.

• Aspartate amino transferase (AST): Another liver enzyme, AST levels can reflect hepatocytes damage caused by various conditions such as viral infection, hepatic necrosis, or drug toxicity.

A comprehensive panel of enzymes allows medical professionals to diagnose various diseases more accurately by assessing the enzyme levels and their specific isozymes.